Low-maintenance, walk-behind wet/dry concrete grinder/polisher

ABSTRACT

A walk-behind, wet/dry grinder/polisher adapted for concrete floors does not use of pulleys, belts or chains. Maintenance is significantly enhanced, as such components are typically the first to wear out and cause replacement issues. A frame with forward and rear portions pivots about a single set of right and left wheels. A planetary grinding head, powered by a propane engine, is coupled to the forward portion of the frame. In contrast to all known designs, the engine is directly, mechanically coupled to the grinding head without the use of pulleys, belts or chains. The direct, mechanical coupling to the grinding head preferably uses a centrifugal clutch. A water tank and water feed line from the water tank to the grinding head facilitate wet floor grinding and polishing. The grinding head is also encased in a shroud coupled to a tube for dust collection associated with dry floor grinding and polishing.

REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S.Provisional Patent Application Ser. No. 63/238,018, filed Aug. 27, 2021,the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to hard floor resurfacing and, inparticular, to a low-maintenance, walk-behind concrete grinder/polisher.

BACKGROUND OF THE INVENTION

Polished concrete floors are becoming increasingly popular forretailers, big-box stores, educational and medical facilities, and evenresidential applications. Common uses include warehouses and warehouseoutlets, hotels and restaurants, office buildings and showrooms.Benefits include low cost, resistance to wear, low maintenance, andaesthetic appeal in many situations. Polished concrete floors are easyto clean, and the glossy surface of polished concrete resists the marksof forklift truck tires and staining from oil and chemical spills. Theglossy appearance of polished concrete is desirable for office building,hotels, restaurants, and other public facilities that want to project abright, clean, professional image.

Various different types of machines are used to achieve a polishedconcrete floor, including riding and walk-behind coarse and finegrinders and polishers using wet and dry techniques. Machines are alsoavailable for stripping and removing old floors, filling in cracks,applying concrete overlays, as well as slurry and dust collection.

The polishing process itself proceeds through a series of mechanical andgrinding stages utilizing professional equipment designed for thesepurposes. The process may also include the use of a concrete “densifier”which penetrates into the concrete to harden and dustproof the surface.The concrete surface is processed through a series of steps withgrinding and polishing disks having progressively finer grits. The disksare typically fabricated with industrial diamonds in a bonded materialsuch as metal, resin or a combination thereof, often referred to as“diamond polishing pads.”

Typically the concrete goes through a process of grinding and polishingusing aggressive equipment and abrasive elements or tooling, includingpads of varying grit from 30 to 3,000. Concrete is considered “polished”until grits of 800 or finer are used, followed by finishing to 15003000-grit levels. The concrete may be ground without entering aggregatelayers, or different sizes of aggregate may be exposed and polished toachieve different appearances. Dyes designed for concrete polishing areoften applied to add color to polished concrete for borders, logos anddecorative patterns. Such options provide a wide range of surface finishand color variations.

Concrete grinding and polishing begins with grinding pads or tools thathave grits of 30, 70, and 120, which are used successively. Theseabrasive elements are rotated at a relatively slow speed during thegrinding steps, e.g., at rotating speeds in the range of about 500 to800 rpm. After grinding with the diamond pads, honing steps follow usinggrits of 50, 100, and 200, rotated at, for example, a speed of about 800rpm. After about 200-grit honing step, dies or stains may be appliedand, if necessary, a concrete densifier may be applied to the floor.

Polishing continues using a 400 grit or finer pad, with rotationalspeeds of the spindles and abrasive elements being in the range of about800 to 1,100 rpm. The concrete will begin to develop a sheen, with thegrit choice of the final polishing steps being dependent upon thereflection and shine desired. If the polishing process is continuedthrough use of a 3000-grit pad, the concrete will assume a mirror-likefinish. Burnishing may further promote a specular appearance. A topicalsealer may be optionally applied to the finished floor.

The grinding and polishing steps may be dry or wet. With the latter, awater tank on-board the grinding/polishing machine delivers water to thediamond pads or resin pads through channels to the polishing head. Withwet polishing, the generated slurry is collected with a squeegee, andwith dry polishing the dust is collected with a vacuum. Typically, thepolishing head is enclosed with a shroud that surrounds the rotatingpads. A vacuum port is connected with a hose to an externally-providedvacuum, which may be nearby or wheeled alongside the grinding andpolishing machine.

Although wet and dry techniques both have advantages and disadvantages,dry polishing tends to be faster, more convenient, and environmentallyfriendly. Wet polishing uses water to cool the diamond abrasives andeliminate grinding dust. The water acts as a lubricant to reducefriction, but cleanup is more involved. Wet polishing creates atremendous amount of slurry that crews must collect and dispose of in anenvironmentally sound manner. With dry polishing, no water is required.Instead, the floor polisher is hooked up to a dust-containment systemthat vacuums up the mess.

In summary, the process of concrete floor polishing may include some orall of the following steps

-   -   Remove existing coating(s);    -   Deposit new layer of concrete onto uneven or damaged floor;    -   Seal cracks, joints or imperfections with an epoxy or other        semi-rigid filler;    -   Progressively grind with a 30/40-, 80- and 150-grit metal-bonded        diamond pads;    -   Optionally apply a chemical hardener to densify the concrete;    -   Progressively polish with a 100/200-, 400- and 800-grit resin or        metal-bonded diamond pads;    -   Apply optional dye(s) for coloration;    -   Finish with a 1500- or 3000-grit resin-bonded diamond pads to        achieve a desired sheen level; and    -   Optionally seal to help protect the polished surface and make it        easier to maintain.

SUMMARY OF THE INVENTION

This invention improves upon the prior art by providing a walk-behind,wet/dry grinder/polisher adapted for concrete floors that does not useof pulleys, belts or chains. By eliminating the use of such“consumables,” maintenance is significantly enhanced, as such componentsare typically the first to wear out and cause replacement issues.

The grinder/polisher is constructed around a frame having forward andrear portions that pivots about a single set of right and left wheels.The rear portion of the frame includes a handle bar assembly. An engineis mounted on the frame, and a planetary grinding head, powered by theengine, is coupled to the forward portion of the frame. In contrast toall known designs, the engine is directly, mechanically coupled to thegrinding head without the use of pulleys, belts or chains.

In the preferred embodiment the engine is a propane engine, and thedirect, mechanical coupling to the grinding head uses a centrifugalclutch. A water tank and water feed line from the water tank to thegrinding head facilitate wet floor grinding and polishing. The grindinghead is also encased in a shroud coupled to a tube for dust collectionassociated with dry floor grinding and polishing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front, perspective view of a preferred embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

There are numerous walk-behind floor grinders and polishers, but theyall use belts, pulleys or chains to couple the motor to the grindinghead. This creates substantial maintenance issues, since theseconsumables are often the first components that need replacement, and ifsuch replacement is required during a job and parts are not available,significant unwanted down time may be encountered.

This invention improves upon the existing art by providing a walk-behindfloor grinder/polisher wherein the engine is directly, mechanicallycoupled to a planetary grinding head, thereby eliminating the need forbelts, pulleys or chains.

FIG. 1 is a front, perspective view of a preferred embodiment of theinvention, depicted generally at 100. The machine includes a frame 122to which there is mounted an engine 114, which in this case happens tobe a propane engine fed by a propane tank (not mounted). The engineincludes an air intake 113 and catalytic exhaust 116 to reduceemissions.

The frame couples to a handle bar assembly 102 with right/left handles103. The handle bar assembly 102 is hinged to the forward portion of theframe through a pivoting joint 104 with locking pins 105 enabling thehandle bar assembly 102 to be adjusted and folded down for more compacttransport. Various user controls are available on the handle barassembly 102, including ignition switch 108, throttle 110,hour/tachometer 109 and emergency stop button 106,

The machine may be used for dry or wet grinding or polishing. For wetprocessing, water from tank 112, feeds the abrasives through water line118. A floating shroud 120 (or rubber equivalent) covers the grindinghead, and exhausts out tube 126 for dust collection if dry processing isused.

The unit pivots about right/left wheels 128, with gas springs 124 beingused for weight distribution. While not visible in the photo, the engine114 is directly coupled to the planetary grinding head through acentrifugal clutch. The clutch is between the engine and a middle gearbox that acts as a speed reduce and torque increaser (2:1). Electric andmanually engaged clutches may be implemented as alternatives tocentrifugal. The middle gear box is bolted to the main planetary gearboxand, in turn, rotates the planetary heads. All rotational power istransmitted through shafts with keyways.

In contrast to all known designs, the engine is directly coupled to thegrinding head without intervening belts, pulleys or chains. Thissubstantially simplifies maintenance issues, since these consumables areoften the first components that need replacement, and if suchreplacement is required during a job and parts are not available,significant unwanted down time may be encountered.

1. A walk-behind, wet/dry grinder/polisher adapted for concrete floors,comprising: a frame having forward and rear portions that pivots about asingle set of right and left wheels; the rear portion of the frameincluding a handle bar assembly; an engine mounted on the frame; aplanetary grinding head coupled to the forward portion of the frame andpowered by the engine; and wherein the engine is directly, mechanicallycoupled to the grinding head without the use of pulleys, belts orchains.
 2. The grinder/polisher of claim 1, wherein the engine is apropane engine.
 3. The grinder/polisher of claim 1, wherein the engineis directly coupled to the grinding head through a centrifugal clutch.4. The grinder/polisher of claim 1, further including a water tank andwater feed line from the water tank to the grinding head facilitatingwet floor grinding and polishing.
 5. The grinder/polisher of claim 1,wherein the grinding head is encased in a shroud coupled to a tube fordust collection associated with dry floor grinding and polishing.